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Convertible Notes (Schedule of Notes) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Nov. 17, 2017	Aug. 16, 2013
Debt Instrument [Line Items]
Total convertible notes	$ 148,788	$ 141,934
Less current portion	0	0
Total long-term convertible notes	148,788	141,934
Convertible notes \| 1.375% convertible notes
Debt Instrument [Line Items]
Face value	172,500	172,500	$ 172,500
Unamortized discount	(22,163)	(28,517)
Unamortized Debt Issuance Expense	$ (1,549)	$ (2,049)
Convertible notes \| 1.125% Convertible Senior Notes due 2018
Debt Instrument [Line Items]
Face value				$ 138,000